As the swine production industry has evolved from the status of a supplement to farming, to that of a major enterprise with production in intensified units, modern confinement facilities for the hogs and pigs have been developed. These facilities require the application of increasingly refined principles of breeding, nutrition, physiology, and environmental control so that the hogs can be developed to economically produce maximum quality products. With respect to swine management, the primary object is to minimize environmental factors which are adverse to the swine so as to provide maximum opportunity for survival and growth. It is also necessary to maintain survelliance over the pigs so that adverse health conditions can be detected before spreading to other healthy pigs.
Since the young pigs are weaned at increasingly shorter periods following their birth, critical health problems have developed that reduce the survival rate of the pigs. Particularly, exposure to adverse environmental conditions results in an increasing risk of infection and starvation that reduces the number of pigs that survive for finishing or breeding. Thus, nurseries for raising weaned pigs have been specially adapted to control the climate within the nursery so as to minimize the losses from the litter.
In the usual arrangement for a nursery of this type, two rows of pens are provided along the length of the shelter with the pens placed in a side-by-side arrangement adjacent each other. The pens permit separation of the pigs into small groups to limit animal contact, which inhibits the spread of disease, and to thereby promote the growth and development of the pigs. A center aisle between the rows of pens provides access to the pens and permits visual inspection of the pigs within the pens. The flooring of the shelter, which supports the pens and pigs, is typically raised so as to form a pit beneath the flooring. Furthermore, the flooring is usually slotted to permit passage of the animals' waste through to the pit below. The slotted floors not only reduce or practically eliminate floor cleaning, but also greatly retard the spread of disease and parasites by allowing the rapid removal of excrement the pens. Additionally, the slotted floor is an essential component in controlling the atmospheric environment of the nursery, in that the air is circulated down through the slots to control the temperature and diffusion of odors.
The survival and development of the pigs within the nursery is dependent on proper control of ambient temperatures within the facilities. The younger the pig when weaned, the more dependent it is upon supplemental heat from the environment since young pigs are incapable of maintaining their own body temperature. Typically, it is desirable to maintain a temperature of 75.degree. to 78.degree. F. for the weaned pigs, with the higher temperature being preferred for pigs weaned at earlier ages.
Prior methods of supplying supplemental heat for the weaned pigs have incorporated independent heating systems that direct radiant or convective heat toward the pigs. Thus, in some facilities, heat lamps are positioned above the pens in which the pigs are contained, and the pigs congregate around the areas in which the lamps are directed so as to be warmed thereby. The inefficiency of radiant and convective heat supplied in this manner diminishes the economy of production, and furthermore, maintenance of the desirable temperature is not easily controlled.
Other methods of supplying supplemental heat to the pigs have incorporated systems for heating the entire nursery. As shown in U.S. Pat. No. 4,018,271, to Jones et al., U.S. Pat. No. 3,826,230, to Jones, et al., and U.S. Pat. No. 3,809,014, to Jones et al., these heating systems adapt the flooring of the facility for circulation of a heated fluid therethrough whereby heat is supplied by conduction and radiation. In a typical construction there is provided a slotted floor composed of individual slats positioned in a parallel spaced arrangement and supported at their opposite ends. The slats, which have been formed from precast concrete, aluminum, or thermoplastic materials, include conduits that are embedded within each individual slat for circulation of a heated fluid through the slat. The conduits are interconnected to form a continuous system, and thereby the complete surface of the flooring is heated as heat is conducted from the fluid.
Since the number of pigs in each of the pens in the nursery is deliberately limited to provide room for growth of the pigs and a suitable environment for the development of the pigs, supplying heat to the entire flooring surface of the pens is inefficient and wasteful. Furthermore, with the entire surface of the pen being heated, the complete area is comfortable for the pigs to occupy and they tend to scatter throughout the pen. Thus, visual inspection of the pigs is difficult, and access to the pigs cannot be easily accomplished without entering the pen.
Furthermore, construction of the flooring for nurseries has been substantially simplified with the development in recent years of floor sections containing a plurality of slats and which are integrally formed by casting reinforced concrete. These integral floor sections are commonly referred to as gang slats. The gang slats are supported at opposite ends on the peripheral and center walls of the farrowing house in a manner similar to the installation of the individual slats, but there is an additional advantage in that installation is convenient. So far as can be determined, no one has heretofore provided any type of built-in heating means with gang slats and with which this invention is particularly concerned.